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SWL for Newbies (was: Balcony Antenna for Shortwave Listening)
On Sun, 12 Dec 2010 12:25:59 -0800, Richard Clark wrote:
On 12 Dec 2010 13:59:06 GMT, Sébastien MEDARD wrote: What you are talking about is common to DXing. Get yourself a globe of the world. Light it up with an artificial "sun." The edge of the dark/light should be half way between you and the transmitter you want to hear. So, during the late day, your best signals are probably from Eastern Europe, Turkey, and Asia. During the early-to-late night, your best signals are probably from the Americas. During the late afternoon to early evening you best signals are from the south or the north. I understand better what is the purpose of this kind of map (on SDR- Radio.com software for example). Where you can see an OM, you are pretty sure to see this kind of map. I need to know a little bit more about digital transmission modes... To be able to recognize digital patterns (on the waterfall display) to be able apply the good settings for decoding... Easy for CW... Easy for RTTY used by HAM... But what is the pattern for Meteo Faxes for example...? When I used to teach RTTY there were only two tones. The reason why they call you OM ? ) By the way... I searched for good free software to decode meteo faxes... But it seems not easy to find something free and easy to use... Do you know shere I could find something interesting? Nope. OK. I will try that later... For now I get some problems to use Linrad with the SDR-IQ... Painful to boot on windows every time I want to listen to shortwaves... And using a virtual system is not very efficient on my old computer... My next tries will be on a multiple turns loops. With or without matching loop inside. I will try with simple wire but connection ribbon cables could be a good alternative... (like old hard drive ribbon cable) This will reveal the "Law of Diminishing Returns" (the more you add, the less you get back). Interesting. What would be the best ratio? I was wondering... It seems loop antennas are a never ending story. So, there you have a century of technical perspective on the topic. ) Perhaps the "Joe Carr's Loop Antenna Handbook" may be interesting, but it is quite expensive and an Amazon reviewer says it is not so interesting... What about the "Joe Carr's Receiving Antenna Handbook" ? He is a respected author. I always look at the bad Amazon reviews to see if something is terribly wrong with the product or terribly wrong with the customer. Quite often the customer is disappointed because that customer is stupid. If I encounter a smart customer that is disappointed, I can well imagine all the good comments are not very reliable. I will try to find one when they are cheaper. The thing about all these -um- books is that many of them serve up old wives' tales about low noise and other magical characteristics. Remember the lessons of a century worth of experience with loop antennas within an inch of the guts of any radio. That worked fine for a billion radios and radios were not bought if they were "noisy." OK. But today we probably ask more to radios than yesterday, no? The real science of low noise is found in the distance to the source. Lapalisse would have said exactly the same thing. He would have said that the real science of good reception is found in the distance to the source too ) Is the loop quieter because of its magic design - or simply because it is 10 times further away (20dB) from the noise? OK for that. We get writers here who pound the table because their magic loop in the shack is noisy and their long wire 10M away in the back yard is quiet. They have to be told to turn off the flourescent light in the shack if they want their magic loop to work. (Their magic loop low score on Amazon) = (stupid.) Lesson one = learned. Thanks. Sebastien. |
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